On a day when they traded for a designated hitter presumably to bolster their tepid offense, the Mariners served up another frustrating reminder of why they made the deal to acquire Kendrys Morales and why they may need to make one or two more deals for additional help.

The Mariners managed just five hits — five singles — in a lackluster and feckless 4-0 loss to the Baltimore Orioles on Thursday night at Safeco Field. They fell to 53-49 and lost their lead in the race for the second wild card.

“We are not swinging the bat well right now,” manager Lloyd McClendon said. “We just have to keep grinding it out. Tonight was not a pretty night. When you don’t hit, you don’t look good, you look flat and all things.”

All five hits call came off Orioles starter Wei-Yin Chen (11-3), who pitched eight shutout innings and issued one walk and struck out two.

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The walk was the closest the Mariners came to scoring. James Jones coaxed the walk from Chen to start the game. He stole second and moved to third on Stefen Romero’s ground ball to the right side.

But Jones was thrown out at the plate on Robinson Cano’s swinging bunt. Chen made a nice play, coming off the mound, fielding the ball and flipping it from his glove to catcher Caleb Joseph, getting Jones as he slid in.

McClendon asked for a replay of the play under the new plate/collision rule, asserting that Joseph was blocking the plate before he had the ball.

“His foot was in the way,” Jones said. “I didn’t understand the rule, if I could run through him or what. I didn’t know what to do. He was definitely in front of the plate. The only thing I could have done is slide away and hit the plate from the side (with his hand).”

The Mariners had no other legitimate scoring opportunities.

Meanwhile, Mariners starter Hisashi Iwakuma (8-5) pitched six scoreless innings in his seven-inning outing. But that one inning — a four-run third — torpedoed the start and put the Mariners behind 4-0 — a deficit, which seems to be insurmountable of late.

Iwakuma gave up three straight singles to start the inning, with Nick Markakis driving in Ryan Flaherty on the third hit to put the Orioles up 1-0. Iwakuma wished the next hit would have been a single. He hung a 79 mph slider to designated hitter Delmon Young, who hit a rocket line drive over the wall in left field for a three-run homer.

“I was trying to get a slider down and away for a strike,” Iwakuma said through translator Antony Suzuki.

It was one of a few mistake pitches — all in that inning.

“He elevated three pitches; other than that he threw the ball good,” McClendon said.

Iwakuma was fighting his mechanics.

“I didn’t start too well today,” Iwakuma said. “I was flying open. I was trying to make the adjustment on the mound. I was able to make the adjustment at the end, but it was too late.”

How bad was the offense?

Chris Taylor, who was called up before Thursday’s game, received a standing ovation from the announced crowd of 19,621 for his first major-league hit.

“It felt great,” Taylor said. “It took some of the weight off my shoulders. I was able to finally relax and breathe. It felt good to get that first one.”